1. Field of the Invention
The invention relates to the use of a new class of biopolymer-based adhesives that are nano- and/or microparticle, which comprise a biopolymer such as starch, in various adhesive applications. These biopolymer latex adhesives can be applied as replacement solutions for synthetic latex adhesives for a variety of applications to porous and non-porous substrates.
2. Description of the Related Art
WO 00/69916 describes a process for preparing biopolymer nanoparticles using an extrusion process, wherein the biopolymer, for example starch or a starch derivative or mixtures thereof, are processed under high shear forces in the presence of a cross-linking agent. This patent application also describes starch nanoparticles, aqueous dispersions of said nanoparticles, and an extrudate prepared by the process which swells in an aqueous medium and forms a low viscous dispersion after immersion. The particles are also described as having a narrow particle size distribution with particle sizes below 400 nm, and especially below 200 nm, and are further characterized by their viscosity. Various applications are mentioned for use of the nanoparticles. However, no examples are provided to demonstrate the adhesive characteristics of the biopolymer latex nor are any specific adhesive applications mentioned.
WO 00/40617 describes a method for the preparation of starch particles in a two-phase system. The resulting starch particles are small and controllable and can range from 50 nm to 100 μm in diameter. As in the previous patent, various applications of these particles are mentioned. However, no examples are provided to demonstrate these applications.